#define _CRT_SECURE_NO_WARNINGS 1


#include <stdio.h>

int main()
{
	double s = 0.0;
	scanf("%lf", &s);
	int count = 0;
	double one = 2.0;
	double sum = 0;
	while (sum<s)
	{
		s -= one;
		one = one * 0.98;
		count++;
	}
	printf("%d", count);
	return 0;
}